the dorbel daily

Friday, 29 April 2011

The Big Quiz, Part 4

In the match I played bar/22, 13/10*, 6/3(2). It's a huge blunder. I was seduced by the better disribution of builders when the 6pt is unstacked, but the play has fatal flaws. It leaves 7 numbers to hit the blot on the 10pt instead of 2 and it doesn't make the 5pt. Not only is the 5pt a far better point to own than the 3pt, but also four points made in a solid block are superior to 4 points made out of six. The best play is clearly bar/22, 13/10*, 8/5(2) making the best point, keeping the return shots to a minimum and damn the bad distribution. Bar/22, 13/10*(3) is also a blunder. It threatens to make points it's true, but making points always beats threatening to make them and the midpoint may yet be valuable. 2 points for making the 5pt and nothing for any other play.
The rest of the game was very dull. White entered hitting my blot on the 3pt, I entered awkwardly got attacked and closed out and just about saved the gammon.

Game Two, White 1 Blue 0 to 5.

I play first with a 6-4.

How do you play this? We'll find out tomorrow. Until then, enjoy the game!

Thursday, 28 April 2011

The Big Quiz, part 3

You'll have been reading recently (fibsboard) about how we need to allocate more thinking time when we roll a doublet and the move isn't clear. What do we need to think about? I like to gather information and the first piece is the pipcount, cunningly not displayed in yesterday's post, so that you had to count it for yourself, just as you would in live play. After this roll, Blue leads 134 to 158. Given an average White roll Blue will come on roll next turn with a 16 pip lead. With that sort of lead there's no reason for Blue to stay back and 22/10(2) is clearly correct. If you're ahead in the race, move forward, if you're behind in the race, stay back. Not rocket science is it?

This is one of those doublets that allows us to move from one type of game to another. Before the roll both sides had two men back and were struggling for position. This giant roll allows Blue to switch two men from a weak anchor to a strong outfield point, so that suddenly he is bearing in, either against an anchor or against one or two blots. Clem is worried that with all his men on four points Blue is a bit stacked, but closer inspection reveals that the situation is a lot more flexible than it looks. All the doublets play well next turn and 16 other rolls make the bar, 5 or 4pts. All the other rolls can be played leaving an outfield blot at the worst, except 6-5 and Blue will even get away with that if White moves up next turn.

22/10(2) is clearly best, score two points for that. No points for 22/16(2), 13/7(2) a medium size error and anything else is a huge blunder! One reason for the strength of making the 10pt is that from there, Blue can usually move serenely towards a nice doubling position, building a prime or blitzing or just racing home as the dice dictate. The plays that include hitting comit Blue to an attacking policy, without the option to prime and with a deep point made that isn't very useful as a landing point in the race variations.
In the match I played 22/10(2) as advertised and then the plays went like this
White 3-1, 8/5, 6/5
Blue 6-3, 13/7, 10/7
White 5-3, 23/15*
Blue 3-3.....................

Another doublet, several choices, what would you do? We'll find out tomorrow. Until then, enjoy the game!

Wednesday, 27 April 2011

The Big Quiz part 2.

Well, two plays really stand out here. We can discard 13/7, 13/11. 28 shots (without including the numbers that hit in White's home board) and the opportunity for White to hit twice is a bit too big. 13/7, 8/6 is a little better, but still 28 shots. 8/6, 8/2* is a lot less shots, only 18 but strips the 8pt of its last builder and stacks the 6pt even higher. This brings us down to 13/5 which I played in the match, 24 shots but slots a very valuable point and duplicates fours for White to hit on the other side of the board. It's a good play, but slightly inferior to the dynamic 13/11, 8/2*, 20 return shots for White but crucially taking away half of White's next roll, limiting her choices and giving her some awkward numbers. This hitting to keep your opponent off balance is a key weapon in the opening, even when it involves hitting deep in the board. I don't do it often enough.
So, two points for 13/11, 8/2* and one point only for 13/5. Nothing for anything else, as all the other choices are blunders.
Then the play went like this. Blue 6-2, 13/5
White 5-1, 8/2*
Blue 4-2, bar/23*, 5/1*
White 4-1, bar/24*, bar/21
Blue 3-1, bar/22, 23/22
White 6-4, 21/11 (probably correct)
Blue 6-6,........................

There is an interesting thread on fibsboard about doublets and the difficulty in playing them. This is obviously a great roll for Blue, how should he play it? By all means post your answer as a comment, no need to be shy!
I'll tell you the answer tomorrow. Until then, enjoy the game!

Tuesday, 26 April 2011

The Big Quiz

Today I'm going to start a match play quiz. These are taken from a match on GridGammon against a strong Japanese player called shirofukurou, about whom I know nothing except that he plays a terrific game. We'll start at the beginning of this five point match and work our way through, asking questions every now and again. Shirofukurou has the White checkers, I'm playing the Blue and the home boards are on the right. Note that when recording the plays, the points used are always from the point of view of the player on roll.
So far the play went like this, Blue 6-5, 24/13.
White 5-1, 24/23, 13/8.
Blue 5-1, 24/23, 13/8.
White 4-2, 8/4, 6/4.
All pretty clear so far, but now it's Blue to play 6-2 and the position looks like this.

There are only seven legal plays, so which of these five do you like?
(a) 13/7, 13/11.
(b) 8/2*, 8/6.
(c) 13/5.
(d)13/11, 8/2*.
(e) 13/7, 8/6.

Tomorrow (I promise) I'll have the answer for you. Tune in

Thursday, 14 April 2011

Here Comes The Snowman

Here are three interesting doubling positions from a Fibs league match with roadkillbooks, a very strong player from Argentina. It's 1-1 to 9 and rkb playing White turns the cube in this position.

I almost passed this one, which would have been a an error, but not a big one. My take was based on the few rolls where White failed to cover, 6-6, 5-4, 4-3, 4-1, 3-1, coupled with some chances if she covered and I entered with a 1 and of course the chances that White may never escape both her back men. This is so close to a marginal take/pass that it is worth remembering as a reference position. In round figures, the rollout shows White winning 65% of the games, of which 35 are gammons. Blue wins a few gammons himself of course and the cube ownership is very useful. So, correct cube action on both sides.

Well, I managed to enter on the ace and jumped out, just as White escaped his last man and got hit, to leave us in this position.

I redoubled to 4, thinking that if I made the 6 prime, White wouldn't be able to take. In fact that is completely unrealistic. A six prime which has 15 checkers is pretty well unbeatable, as the spares allow a great deal of choice while you roll it home, but here I only have 13 checkers to arrange and this will give White a lot of opportunities to hit a fly shot and/or jump out, where her race lead and cube ownership will come into play. So, even if I make the prime, I will still be short of a redouble! I have to wait until I can put White on the bar and double her out if she flunks. I need 24% incorrect passes to make this redouble right and I don't think I have that many. White took.

That took us on the third big cube decision of this game.

I had to hit loose as White was at the edge of a five prime, White hit back from the bar and I danced. Here comes the snowman. This is a fairly easy take of course, as I am on the bar, so if nobody rolls a 6 I keep my prime while his board goes down the drain. Technically it isn't even a redouble until he escapes, because the double kills the gammons. For money you can redouble this, still an easy take of course.
These three positions are all good ones to remember and playing them out yourself a few times is a good idea, partly to understand what can happen from here and partly to cement them into your brain.
If you find yourself playing roadkillbooks, good to remember that he isn't frightened to use a recube, not the sort of fellow you want to double in early!
Note that I always use the she pronoun for the White pieces, so you know which side I am talking about. Roadkillbooks is not a she. Until the next time, enjoy the game!